We have investigated neurotransmitter metabolites and glucose metabolism in incarcerated violent offenders, arsonists and healthy volunteers. We have found that low cerebrospinal fluid (CSF) 5- hydroxyindoleacetic acid (5HIAA) concentrations and hypoglycemias during oral glucose tolerance tests are associated with each other and impulsive violent acts and fire setting. In a follow-up study we found that a low blood glucose nadir and low CSF 5-HIAA concentration were powerful predictors of recidivism among impulsive violent offenders and fire setters. We are currently collecting lymphocytes from violent offenders, their family members and appropriate controls.